let btn = document.getElementById("fuck");
let val = document.getElementById("time");
let ti = val;
btn.disabled = true;

let reduce = setInterval(() => {
  ti -= 1;
  val.innerHTML = ti;
}, 1000);
let t = setTimeout(() => {
  btn.disabled = false;
  alert("可以跳转了");
  clearTimeout(t);
}, 3000);
